Electrical resistance unit



Sept. 6, 1932. c. WEICHELT 1,876,116

ELECTRICAL RESISTANCE UNIT Original Filed Aug. 7. 1929 INVENTOR ,4;

ATTORN EY J Patented Sept. 6, 1932 UNITED STATES PATENT OFFICE CARL L. WEICHELT, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR '10 WIBT COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF MAINE ELECTRICAL RESISTANCE UNIT' Original application filed August 7, 1929, Serial No. 884,105. Divided and this application filed August 8, 1980. Serial No. 478,789.

This invention relates to electrical resistance units of a newand improved construction, the object of which is to provide a device of this character which may be made in a flat or linear form and subsequently bent into arcuate shape if desired. Another object of my invention is to provide a resistance which maybe constructed as a unit of which two or more may be connected together endwise to provide the desired resistance and which when so connected may shaped into a circle for convenient mounting in a protective shell or casing and for cooperation with a rotatable contact brush or wiper.

ends the invention consists in certain improvements in elements, their combination and other features all as will be more thoroughly explained and the novel features ointed out in the appended claims.

The present application is a division of the original application Serial No. 384,105, filed August 7, 1929 and relates to the resistance unit shown, described and originally claimed therein.

- In the drawing Figs. 1 and 2 are perspective views showing the novel means of forming a support for a resistance wire to be wound thereon; Fig. 3 illustrates one of the completed units shown in Fig. 2 with a resistance wire wound thereon, and Fig. 4 shows one way in which the resistance units may be utilized in variable resistance devices such as that described in my original application.

A novel means which I have devised for constructing the support of a resistance unit comprises the provision of two metallic strips 1 and 2 (Fig. 1) which together form a rigid support on which to wind a resistance wire. Each of the strips is bent over at one end as shown at 7 and 8 and a sheet of insulation 4, such as a sheet of asbestos, positioned between said strips so as to permanently insulate them. One end of the insulating strip 4 is clamped in the bent end of one of the metallic strips and the other end of the insulating strip is cl amped in the bent end of the other metallic strip as shown in Fig. 1. The insulating strip 4 is of such length that when the two metallic strips, having been clamped upon it,

To these and other lie against it, there is a spaoe'between the bent end of one metallic strip and the plain end of the other metallic strip so that the are completely insulated from each other. his method of construction insures perfect insulation and a substantially uniform thickness of the supporting structure.

. The assembled strips 1 and 2 with the sheet 4 therebetween are covered with a suitable protective insulation such as by wrapping thereon several layers of an asbestos sheet 5 as shown in Fig. 2, the-bent end portions 7 and 8 of the support being preferably left uncovered or exposed. These end portions may be provided withsuitable holes 10 for the connection of supporting fixtures and electrical connections.

A resistance wire 11 is wound upon the insulation 5 as shown in Fig. 3. By connecting one or both ends of the resistance wire to the uncovered end portions of the metallicstrips by looping the wire through one of the "open ngs in said end portions and securing it therein, any desired electrical connection with the resistance wire may be made through one or both of the uncovered end portions. Consequently, the supporting fixtures may serve as electrical connections.

In Fig. 4 I have shown how two of these resistance units may be utilized together to form a circular rheostat. I have shown two units 13 and 14, each bent to semi-circular form and connected to supporting brackets 16 and 17 by means of rivets 19 and 20. One or both of the said brackets may serve also as electrical connection for the rheostat. I have shown the rheostat as enclosed in the casing 21 of a resistance device such as that of myapplication No. 384,105, the casing 21 being lined with insulation 22. It will readily be seen that the resistance wire 11 may be connected to both of the ends 7 and 8 or left out of contact with one end in accordance with the circuit arrangement which it is desired to use.

This method of constructing a resistance unit affords a rigid unit which'may nevertheless be bent to any desired form after the resistance wire has been wound on it, 100

thus facilitating its manufacture. An additional advantage is that the support itself supplies rigid means for making electrical connection to both ends of the resistance wire without the use of any additional members especially for that purpose.

The invention has been described and illustrated by the portrayal of a structure which in practice has proved to be a satisfactory commercial embodiment thereof but it is understood that the structure shown is merely illustrative and the invention may be carried out in other ways.

I claim.

1. A resistance unit comprising a support consisting of two conducting strips, each strip having a folded end, the inner edges of said folded ends being spaced from the extremities of the non-folded ends, insulation between the two strips and clamped in their folded ends, other insulating material covering the support between the folded ends of the strips, and a resistance element wound on said last mentioned insulation.

:5 2. A resistance unit composed of two similar fiat pieces of metal disposed parallel to each other, each having a portion bent over at one end, a strip of insulating material secured at its extremities in said ends of the strips and of suflicient length to maintain the contiguous ends of said strips out of contact; a wrapping of insulation enclosing the two strips and a resistance wire wound upon said wrapping.

In testimony whereof, I have signed this specification.

. CARL L. WEICHELT. 

